OFDM and OFDMA wireless communication systems under the Institute of Electrical and Electronics Engineers (IEEE) 802.16 use a network of base stations to communicate with wireless devices (i.e., mobile stations) registered for services in the systems based on the orthogonality of frequencies of multiple subcarriers and can be implemented to achieve a number of technical advantages for wideband wireless communications, such as resistance to multipath fading and interference. Each base station (BS) emits and receives radio frequency (RF) signals that convey data to and from the mobile stations (MSs).
In an effort to conserve power at the MS, the IEEE 802.16 standard defines a sleep mode having different types of power saving class (PSC), where the MS may power down one or more components during sleep windows. The MS may periodically wake up to monitor for activity (e.g., a traffic indication message or other PSC active state termination message) during listening windows to determine whether the sleep mode should be exited. However, the MS generally powers up components during the listening window, thereby consuming battery power. Furthermore, a missed message may prompt the MS to search on neighbor channels or wait for the next message while at a full power state, thereby also consuming power.